Proposals by type

Polyfill proposals

Feature	TC39	CoreJS	Babel	Civet	JS+
Temporal	✅ Stage 4	❌	❌	❌	❌
Joint iteration	✅ Stage 3	✅	❌	❌	❌
Atomics.pause	✅ Stage 3	❌	❌	❌	❌
Legacy RegExp features	✅ Stage 3	❌	❌	❌	❌
Iterator chunking	✅ Stage 2.7	✅	❌	❌	✅
Error stack accessor	✅ Stage 2.7				❌
Iterator join	✅ Stage 2.7				❌
Iterator.includes	✅ Stage 2.7	❌	❌	❌	❌
Promise await dictionary	✅ Stage 2.7	❌	❌	❌	✅
ShadowRealm	✅ Stage 2.7				❌
Async iterator helpers	✅ Stage 2	✅			❌
Iterator range (range)	✅ Stage 2	✅			❌
Math.clamp	✅ Stage 2	✅	❌	❌	✅
Reflect.isTemplateObject	✅ Stage 2	✅			❌
Symbol predicates	✅ Stage 2	✅			❌
Async context	✅ Stage 2				❌
Collection (coerceKey, coerceValue)	✅ Stage 2				❌
Error.captureStackTrace	✅ Stage 2				❌
JSON.parseImmutable	✅ Stage 2				❌
Object.keysLength	✅ Stage 2	❌	❌	❌	✅
Promise.isPromise	✅ Stage 2	❌	❌	❌	✅
{BigInt,Number}.fromString	✅ Stage 1	✅			❌
Array filtering	✅ Stage 1	✅			❌
Array.prototype.unique()	✅ Stage 1	✅			❌
Collection methods	✅ Stage 1	✅			❌
Collections of/from	✅ Stage 1	✅			❌
Observable	✅ Stage 1	✅			❌
Richer Keys (compositeKey, compositeSymbol)	✅ Stage 1	✅			❌
String.cooked	✅ Stage 1	✅			❌
Array Equality	✅ Stage 1				❌
Array.zip and Array.zipKeyed	✅ Stage 1				❌
Built In Modules (aka JS Standard Library)	✅ Stage 1				❌
Bulk-add array elements	✅ Stage 1				❌
Cancellation API	✅ Stage 1				❌
Composites	✅ Stage 1				❌
Error frames above	✅ Stage 1				❌
Error option limit	✅ Stage 1				❌
new.initialize	✅ Stage 1				❌
Object pick/omit	✅ Stage 1				❌
Object property count	✅ Stage 1	❌	❌	❌	✅
Object.freeze + Object.seal syntax	✅ Stage 1				❌
Object.getNonIndexStringProperties()	✅ Stage 1				❌
Random	✅ Stage 1	❌	❌	❌	✅
Representing amounts	✅ Stage 1				❌
Signals	✅ Stage 1				❌
String.prototype.codePoints	✅ Stage 1				❌
TypedArray concat	✅ Stage 1				❌
TypedArray find within	✅ Stage 1				❌
Function.prototype.demethodize	✅ Stage 0	✅			❌
Reflect.{isCallable,isConstructor}	✅ Stage 0	✅			❌
{Set,Map}.prototype.toJSON	✅ Stage -1				❌
ArrayBuffer.prototype.transfer	✅ Stage -1				❌
Builtins.typeOf() and Builtins.is()	✅ Stage -1				❌
Math Extensions	✅ Stage -1				❌
Math.signbit: IEEE-754 sign bit	✅ Stage -1				❌
Symbol.thenable	✅ Stage -1				❌

Syntax proposals

Feature	TC39	CoreJS	Babel	Civet	JS+
Decorators	✅ Stage 3	✅	✅	❌	✅
Import defer	✅ Stage 3		❌	❌	❌
Using	✅ Stage 3		❌	❌	❌
Import bytes	✅ Stage 2.7				❌
Extractors	✅ Stage 2	✅			❌
Deferred re-exports (export defer)	✅ Stage 2				❌
Destructuring private	✅ Stage 2				❌
Discard binding	✅ Stage 2		✅	❌	✅
Function implementation hiding proposal (hide source directive)	✅ Stage 2				❌
Function sent	✅ Stage 2		✅		❌
Import sync	✅ Stage 2				❌
Module declarations (module blocks)	✅ Stage 2		✅		❌
Pipeline operator	✅ Stage 2		✅	✅	✅
RegExp buffer boundaries	✅ Stage 2				❌
Seeded pseudo random numbers	✅ Stage 2				❌
Structs	✅ Stage 2				❌
Throw expressions	✅ Stage 2		✅	❌	✅
Pattern matching (match)	✅ Stage 1	✅		✅	❌
Alias accessors (alias)	✅ Stage 1				❌
Composable accessors (@memoized, @validate, @normalize)	✅ Stage 1				❌
Decimal	✅ Stage 1				❌
Enums	✅ Stage 1				❌
Export default from	✅ Stage 1		✅	❌	✅
Negated in and instanceof operators	✅ Stage 1				❌
Partial application	✅ Stage 1		✅		❌
RegExp \R Escape	✅ Stage 1				❌
RegExp Atomic Operators	✅ Stage 1				❌
Slice notation	✅ Stage 1				❌
Type annotations	✅ Stage 1				❌
as destructuring patterns	✅ Stage 0				❌
Async do expressions	✅ Stage 0		✅	✅	✅
Do expressions	✅ Stage 0		✅	✅	✅
Function bind syntax (::)	✅ Stage 0		✅		❌
deprecated	✅ Stage -1				❌
from ... import	✅ Stage -1				❌
Rest everywhere	❌		❌	✅	❌
String.prototype.at	✅ Stage -1				❌
use module	✅ Stage -1				❌

Runtime proposals

Feature	TC39	CoreJS	Babel	Civet	JS+
Binary AST	✅ Stage 1				❌
Chained comparisons	❌		❌	✅	✅
Eval checks	✅ Stage 3		❌	❌	❌
Import text	✅ Stage 3				❌
Non-extensible applies to private	✅ Stage 3		❌	❌	❌
Source phase imports	✅ Stage 3		✅	❌	❌
ESM module phase imports (workers import defer)	✅ Stage 2.7				❌
Immutable ArrayBuffers	✅ Stage 2.7				❌
String dedent	✅ Stage 2	✅		✅	❌
Jobcallback module	✅ Stage 2				❌
Module expressions	✅ Stage 2				❌
Compare strings by codepoint	✅ Stage 1	✅			❌
Change Number.parseInt/parseFloat not to coerce null/undefined/NaN	✅ Stage 1				❌
Compartments	✅ Stage 1				❌
Date.parse uniform parsing	✅ Stage 1				❌
Function Memoization	✅ Stage 1				❌
Inspector	✅ Stage 1				❌
Secure ES	✅ Stage 1				❌
Date.parse fallback semantics	✅ Stage -1				❌
Dynamic import host adjustment	✅ Stage -1				❌
Negative array subscript	✅ Stage -1		❌	❌	✅
Typeof null operator	✅ Stage -1		❌	❌	✅